The present invention relates to packaging of microfluidic devices and, more particularly, to a method for making electro-fluidic connections in microfluidic devices.
Chemical microanalytical systems, also known as xe2x80x9cchemical laboratories on a chip,xe2x80x9d offer the promise of high analytical performance in systems that are small, consume low power, and have low manufacturing and operating costs. Such microanalytical systems require the manipulation of fluids for sample handling, mixing, separation, and detection of analytes. The fluid may be a gas, liquid, or a supercritical fluid. One of the major challenges for making reliable, robust, and low cost microanalytical systems is the assembly of multiple microanalytical components that require both electrical connections and leak free fluidic connections. In some cases, integration can be used to fabricate the microanalytical components and make the connections on a single substrate. However, the many different fabrication processes, chemically selective materials, and dimensions for the various microanalytical components generally favors independently fabricating the component dies and then assembling them together in a hybrid structure. Simple and reliable methods for performing this electrical and fluidic assembly are necessary.
The present invention provides a method for making the electrical and fluidic connections between a microfluidic substrate and a plurality of individual microanalytical components that require fluid flow and comprise active electrical elements. The method is simple and can be used with any microfluidic device wherein reliable fluidic and electrical connections are required.
The present invention is directed to a method for forming an electro-fluidic connection from a microfluidic substrate to a die having at least one active electrical element thereon, comprising forming at least one bond pad on the die that is electrically connected to the at least one active electrical element; forming a seal ring on the die around the outside of the at least one bond pad and the at least one active electrical element; forming at least one matching bond pad on the microfluidic substrate for connection to support electronics; forming a matching seal ring on the microfluidic substrate around the outside of at least one fluidic via hole; bonding the at least one bond pad to the at least one matching bond pad with a conductive sealant to form electrical connection from the microfluidic substrate to the active electrical element; and bonding the seal ring to the matching seal ring with a sealant to form a fluidic seal around the at least one active electrical element and the at least one fluidic via hole. Alternative methods for forming the electro-fluidic connection comprise forming an insulating seal ring on the inside of the electrical bond pads and on the outside of the at least one active electrical element.